Debugger with method restart capability

ABSTRACT

Methods and apparatus for debuggers supporting method restart are described. A method comprises implementing a user interface (UI) enabling a user to submit a request, via a single interaction within a debugging session, to restart execution of an invocable operation of a program. The method further comprises, in response to a request to restart an invocable operation, designating, as the source code line whose corresponding executable code is to be executed next, the first line of source code of the particular invocable operation that corresponds to an executable operation. The method includes indicating that execution of the program is to be resumed at the first line, and resuming execution of the program at the first line.

BACKGROUND

Software engineers typically spend substantial amounts of time debuggingcode, often using fairly sophisticated integrated developmentenvironments (IDEs) with built-in debuggers. In many cases, the debuggeruser interface provides a number of different windows or viewsconcurrently, such as separate windows for showing the call stack of thecurrent thread, breakpoint lists, variable values, source code filecontents, and so on. While the numerous windows or perspectives into thedebugged program may provide very useful information, the workspaces(e.g., computer displays) being used during debugging sessions maytypically become rather busy or full, with little additional room fornew GUI components.

In some scenarios, debugger users may wish to revisit certain parts ofthe program being debugged, often more than once as they try todetermine the root cause of a complex problem. Depending on the specificdebugger and user interface, the available mechanisms to revisit orre-run certain parts of the code may sometimes result in a proliferationof potentially distracting additional windows, panels, or other GUIcomponents. Furthermore, in some cases, the user interfaces may forcethe user to perform multiple actions (e.g., multiple mouse clicks) toimplement some fairly frequently needed debugging operations, resultingin longer, potentially less productive and more irksome debuggingsessions.

SUMMARY

Various embodiments of apparatus and methods for debuggers with methodrestart capability are described. According to one embodiment, a systemmay include one or more computing devices configured to implement acomputer program debugger. The debugger may be configured to implementone or more user interfaces (UIs) enabling a user to submit a request,via a single UI interaction within a debugging session of a program, torestart execution of an invocable operation (such as a method, function,or procedure) included in the source code of the program. In response toa request to restart execution of a particular invocable operation ofthe source code, received via a single UI interaction via one of theuser interfaces, the debugger may designate, as the source code linewhose corresponding executable code is to be executed next during thedebugging session, the first line of source code of the particularinvocable operation that corresponds to an executable operation. (It isnoted that at least in some programming languages, some lines at thestart of an invocable operation, such as lines comprising variabledeclarations or comments, may not have any corresponding executableoperations, and as a result it may not be possible to resume executionat such non-executable lines.) The debugger may indicate to the user,e.g., via a “next line to be executed” icon or pointer in a graphical UI(GUI) component displaying the source code of the program, thatexecution of the program being debugged is to be resumed at the firstline. The debugger may resume execution of the program being debugged,in a debug mode, at the first line of the invocable operation. The term“in debug mode”, as used herein, refers to the fact that the program'sexecution is managed via the debugger UI, enabling the debugger user to,for example, pause the execution at desired points, inspect/modifyprogram state, and resume execution as desired.

In at least some embodiments, the user may choose which specificinvocable operation, among the plurality of invocable operations of acall stack of a particular thread of execution, is to be restarted. Forexample, debug-mode execution may be resumed at the start of theinvocable operation currently executing when the request is received, orat the start of a selected one of the plurality of other invocableoperations in the call stack. In one embodiment, when the request torestart a method is received, no new windows, panels or other GUIcomponents may be instantiated or opened, e.g., to avoid any additionalclutter on the display being used for the debugging session. Thus, inone example scenario in such an embodiment, if there were four distinctwindows or panels open in the debugger GUI at the time a request torestart a method were received, only those four distinct windows orpanels would remain open after the debugger restarts the specifiedmethod (of course, some of the contents of the windows, such as anindicator of line being executed, variable values, and the like, maydiffer after restart).

A variety of different programming languages and/or executionenvironments may be supported in different embodiments. In oneembodiment, the program being debugged may be written in aplatform-independent, object-oriented programming language such asJava™. In other embodiments, programs written in other languages such asC or C++ may be debugged. The execution environment of the program maycomprise a virtual machine (such as a Java™ Virtual Machine or JVM) insome embodiments, and the debugging requests submitted by a user to thedebugger (such as method restart requests) may result in one or morecorresponding internal requests being transmitted to the virtualmachine. In one implementation, for example, in which Java™ is theprogramming language being used, one or more internal requests expressedusing a debugging programmatic interface standard such as JDI (the Java™Debug Interface) may be issued by the debugger to a JVM that supportsJVMTI (the Java™ Tool Interface). To implement the invocable operationrestart capability in one embodiment, a plurality of internal debuggingrequests may be generated, such as, for example, a first request to popthe execution stack of the program to a calling invocable operation fromwhich the particular invocable operation to be restarted was called, anda second request to step into the particular invocable operation to berestarted. It is noted that in at least some embodiments, the executionenvironment of the program may not provide a capability to move anexecution point of the program (e.g., an instruction pointer) to anarbitrary location within the program. Furthermore, in at least someembodiments, a debugger architecture to which the program debuggerconforms may not provide a single-step interface enabling a restart ofan invocable operation. In such embodiments, despite these constraintsof the underlying programming/debugging infrastructure, users may stillbe able to restart invocable operations using a single user interfaceinteraction.

Several different debugger user interfaces may be available to usersthat wish to make use of the invocable operation restart capability invarious embodiments. Such user interfaces may include IDE (integrateddevelopment environment) GUIs that include built-in debuggers,standalone debugger GUIs, or command-line debugger interfaces. In oneembodiment, a component of the debugger UI may display a thread's callstack. A drop-down menu (or some similar GUI element) associated withthat call stack display component may enable a user to submit a requestto restart a particular invocable operation selected from the displayedcall stack. In another embodiment, a context-dependent GUI component mayprovide an action element that a user can employ to restart an invocableoperation, or an action to restart a method may be made available from a“run menu” provided to enable IDE users to run programs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example debugging architecture for programsexecuted in a virtual machine environment, according to variousembodiments.

FIG. 2 is a block diagram illustrating example GUI components of an IDEthat includes a debugger, according to at least some embodiments.

FIGS. 3 a, 3 b and 3 c illustrate respective examples of GUI elementsthat may be used to request method restarts in a debugging session,according to at least some embodiments.

FIG. 4 is a flow diagram illustrating aspects of operations that may beperformed to support restarts of invocable operations during debuggingsessions, according to at least some embodiments.

FIG. 5 is a flow diagram illustrating operations performed to sendrequests to a debuggee, without instantiating any additional graphicaluser interface components, to restart an invocable operation, accordingto at least some embodiments.

FIG. 6 illustrates an example computing device that may be used in someembodiments.

DETAILED DESCRIPTION OF EMBODIMENTS

It is noted that, while for purposes of illustration, the followingdescription is provided largely in the context of debuggers for theJava™ programming language, and to capabilities for restarting Java™methods, the techniques described may be used for other programminglanguages and other invocable operations as well. The term “invocableoperation” may be used herein to refer to methods, functions,procedures, or similar constructs in various programming languages. Insome embodiments, a debugger may be available as an independent orstandalone tool, while in other embodiments, a debugger may beincorporated into an integrated development environment (IDE) used bydevelopers, quality engineers, support engineers and the like duringvarious phases of the software development lifecycle. In one embodiment,a debugger may be built in to an execution environment or console—e.g.,some programming languages may allow users to submit code via acommand-line interpreter or console interface, and debug their codeusing the same interface.

FIG. 1 illustrates an example debugging architecture for programsexecuted in a virtual machine environment, according to variousembodiments. A debugger may be implemented in accordance with anarchitecture defined in a published standard in some embodiments, suchas the Java™ Platform Debugger Architecture (JPDA). In the depictedembodiment, a JPDA-like architecture is used for a debugger 140configured to support debugging of programs being executed in a virtualmachine 110 such as a JVM. The program being debugged may be referred toas a “debuggee” herein. The virtual machine 110 may support debuggingservices or programming interfaces defined in the architecturespecification, such as interfaces defined by the Java™ VM Tool Interface(JVMTI) or the older (and now deprecated) Java™ VM Debug Interface(JVMDI). Such debugging services or programming interfaces may allow theinspection of the state of an application running in the VM, and/or tocontrol the execution of the application, e.g., by setting/disablingbreakpoints, viewing current stack frame contents or the values to whichvarious variables are to be set, modifying variable values, determiningwhich portion of the program is to be executed next during a debuggingsession, receiving notifications when a breakpoint is reached, and thelike. In the Java™ context, JVMTI and/or JVMDI are examples of nativeinterfaces implemented by at least some versions of the JVM on variousplatforms, in contrast to platform-independent protocols such as JavaDebug Interface (JDI) that may be used by debugger front-ends asdescribed below. Similar interfaces may be defined for other programminglanguage environments and/or virtual machine environments in otherembodiments. It is noted that in some embodiments, the debugger may beused for programs that are not executed in virtual machines.

As shown, the virtual machine 110 may include the executable code 115 ofthe program being debugged, and may also include a back-end component120 of a debug communication protocol such as the Java™ Debug WireProtocol (JDWP) in some embodiments. The communication protocol maydefine the format of information and requests transferred between thedebuggee and the debugger 140. In some embodiments, the protocolspecification may allow the debuggee and the debugger to run underseparate VM implementations and/or on separate platforms. The protocolmay support flexible debugger implementations in several ways: forexample, the programming language in which the debugger is written neednot be the same language used for the debuggee, and the details of thetransport mechanism to be used for the communication (e.g., sockets,serial lines, or shared memory) may be left to the debugger implementeras well. A front-end component 130 of the debug communication protocolmay be used by the debugger 140 to interact with the virtual machine 110in the depicted embodiment, e.g., over a debugging communication channel125. In at least some embodiments, a high-level platform-independentfront-end interface 132 (e.g., a Java™ interface such as the Java DebugInterface (JDI)) may be defined in the debugger architecture, enablingvendors to implement debuggers in high-level languages, even though thevirtual machine information actually transmitted via the communicationprotocol may not use that high-level language. The high-level front-endinterface (such as JDI) may, for example, define mirror or proxy classesto examine or manipulate various aspects of the state of the virtualmachine in some embodiments.

In some embodiments the communications may occur across network links(i.e., the VM 110 at which the program being debugged is run may beinstantiated on a different hardware device than the device at which thedebugger 140 runs, and the two hardware devices may be connected via oneor more network links), while in other embodiments, the communicationsmay be confined within a single hardware device (i.e., the VM and thedebugger may run on the same hardware device or host). In at least someembodiments a debugger 140 may be usable for both local and non-localdebugging, i.e., the debugger may be able to connect to remote VMs ordebuggee programs when needed and with local VMs or debuggees as needed.In one embodiment a debugger 140 may be used to debug more than onedebuggee concurrently—e.g., in a producer-consumer scenario where twoprograms are communicating, the same debugging session may be used todebug the operations of both the producer program and the consumerprogram.

A number of different user interfaces 150 may be implemented by thedebugger 140, such as one or more GUIs, command-line interfaces and thelike. In some embodiments the debugger interface may be combined with,or be part of, a more comprehensive Integrated Development Environment(IDE) user interface. An IDE may be used by software engineers forvarious purposes other than just debugging in various embodiments, e.g.,for designing, developing, building, testing, or browsing the code,and/or for packaging/deploying the code to application servers or otherexecution platforms. UI interactions 155 between the debugger 140 andits users 160 may include, for example, various action requestssubmitted by the users, such as to start or terminate a debuggingsession, add or remove debugging breakpoints, browse source code 165 ofthe debuggee program, and the like. A debugging session may thuscomprise a plurality of requests from the user 160, and correspondingresponses to those requests by the debugger 140; to respond to at leastsome of the requests, the debugger may send internal requests to thedebuggee or the VM 110 in which the debuggee program runs. In at leastsome embodiments, as a debugging session proceeds, the part of thesource code 165 that is being executed currently may be indicated viaone of the UIs, e.g., by icons or symbols indicating the source codelines whose corresponding executable instructions are run, or indicatingthe source code line that is to be executed next.

In one embodiment, the UI or UIs 150 implemented by the debugger 140 mayenable a user 160 to submit a request, via a single UI interactionwithin a debugging session of a program, to restart execution of aninvocable operation such as a method or a function included in thesource code 165 of the program. It is noted that in at least someembodiments, the execution environment of the program being debugged(e.g., a JVM environment) may not provide a capability to move anexecution point of the program (e.g., an instruction pointer) to anarbitrary location within the program. Furthermore, in at least someembodiments, a debugger architecture to which the program debuggerconforms (such as JPDA) may not provide a single-step interface enablinga restart of an invocable operation. In such embodiments, despite theseconstraints of the underlying programming/debugging infrastructure,users may still be able to restart invocable operations using a requestissued via a single UI interaction. In response to such a request, thedebugger 140 may designate, as the source code line whose correspondingexecutable code is to be executed next during the debugging session, thefirst line of source code of the particular invocable operation thatcorresponds to an executable operation. (Thus, the debugger may notdesignate as the next-to-be-executed line, any source code line at ornear the beginning of the invocable operation that does not havecorresponding executable instructions, such as a line comprisingvariable declarations or comments). In at least some embodiment, visualevidence or indications of the restart of the method, or of the nextline to be executed, may be provided to the user 160, e.g., by modifyingthe location of a cursor or a “next-line” symbol or icon, or changingthe color of the designated first line in a display of the source code165. The debugger may resume the execution of the program in debug modeat the first line. In some embodiments, depending for example on userpreferences or settings, if the first line does not have an associatedbreakpoint, the program may be executed until the next breakpoint (afterthe first line) is reached, while in other embodiments, the debugger maypause execution at the first line by default, allowing the user toindicate whether the code is to be stepped through one line at a time,or whether the code should be executed to the next breakpoint after therestart of the invocable operation.

In some implementations, a user 160 may submit a request to restart anyof various methods of the current thread's execution stack, includingfor example the currently-executing method or any of the methods whoseinvocations led to the invocation of the currently-executing method. Insome implementations, in order to restart a given method M1, thedebugger 140 may submit a plurality of requests to the VM or thedebuggee—e.g., one request to pop the execution stack to M1's callermethod M2, and another request to step into M1 after the stack has beenpopped as requested. In scenarios where one of multiple methods (e.g.,M1, M3 or M4) could have been called from the same source code line inthe calling method M2, e.g., if a chained expression or a conditionalexpression was used to select the method to be called, the method M1whose restart is requested by the user would be stepped into in such animplementation, without requiring any input from the user to select fromamong the multiple options for the next-called method. The fact thatmultiple internal requests were made may not be indicated to the user160 in at least some embodiments—e.g., as far as the user 160 isconcerned, a single action request to restart a method was submitted,and the debugger responded by resuming execution as requested in asingle response step. The internal requests issued by the debugger maybe written in accordance with the high-level debug interface 132 such asJDI in one embodiment. In some embodiments, there may be no change tothe number of windows or panels being displayed in the UI—e.g., if thedebugger was displaying N windows before a restart method request wasreceived, the same N windows would continue to be displayed (althoughcontents of some of the windows may be changed, such as the indicationof the next-to-be-executed line, the values of variables, and so forth).In this way, users 160 of debugger 140 may be able to resume debuggingat the start of a specified method without being distracted byinstantiation of any additional GUI components in such embodiments.

FIG. 2 is a block diagram illustrating example GUI components of an IDEthat includes a debugger, according to at least some embodiments. In theillustrated embodiment, the IDE presents a GUI with a number of distinctwindows or panels, such as windows 220, 230, 240, 250 and 260. In thedepicted embodiment these windows are shown as being contained within asingle encompassing root window 290; however, in at least someembodiments, some or all of the windows may be detachable from the rootwindow 290 based on the user's preferences, and may be arrangedindependently of each other on the display being used. Windows may alsobe rearranged within the root window in some implementations. The IDE UImay include a header line 202, in which the name of the IDE and/or thecurrent source file or source code directory being viewed may beindicated. One or more toolbars showing respective sets of high-level orglobal commands (such as toolbar 204 with options such as “File”,“Edit”, and the like, and toolbar 206 with icon representations ofcommand sets) may be displayed in some embodiments.

During debugging sessions, the IDE UI may include a call stack window220 displaying the execution stack(s) for one or more threads of theprogram being debugged. Window 230 may display a list of the breakpointsthat have been set up in the program, while object/variable browserwindow 240 may show variables or other objects of the program, togetherwith various properties or values of the variables or objects. Window250 may be used to display either a view of the source code hierarchy(e.g., a package hierarchy in Java™ environments), or console contents,depending on the user's preference in the depicted example. Consolecontents may show status information of the debug session—e.g., whetherthe debuggee program is paused at a breakpoint, whether any errorsoccurred, whether the debugger is waiting for user input, and so on. Insome embodiments, the console contents may be shown in a differentwindow than the source code hierarchy.

Source code window 260 may display the contents of one or more sourcecode files of the program being debugged, such as the file namedTest.java in the depicted example. (Multiple source code files may beshown using respective tabs associated with the window 260 in someimplementations). A next-line symbol 261 may indicate the next sourcecode line whose corresponding executable instructions are to be run nextduring the debugging session. Breakpoints, if any, in the displayedsource code may be indicated by breakpoint symbol 263. Each of thewindows displayed in the IDE UI may include a respective toolbar in someembodiments. One or more of the windows may allow users to bring upcontext-dependent menus, e.g., by right-clicking using a mouse withinthe window. One or more of the windows shown in FIG. 2 may allow usersto submit requests to restart methods or other invocable operations, asdescribed below in further detail.

FIGS. 3 a, 3 b and 3 c illustrate respective examples of GUI elementsthat may be used to request method restarts in a debugging session,according to at least some embodiments. FIG. 3 a illustrates a callstack window 220, within which the call stack of the currently-executingthread is shown. The example call stack indicates that a method “depth1”of a class “RMTest” called method “depth2” and that “depth2” called“depth3”. As shown by the selection indicator 305, “depth1” has beenselected by the user. The available commands/actions menu 310 (which mayfor example be displayed in response to the selection of the method, orin response to a right-click after the method is selected) indicates theset of actions that can be requested on the selected method “depth1”.The “Restart Method” option 315 may be used to request a resumption ofexecution of the debuggee program at the start of the selected method“depth1” in the depicted example.

FIG. 3 b illustrates a second alternative that may be available in somedebugger UIs to request method restarts. A context menu 321, which maybe displayed in response to a context-specific click in the debugger GUIor the IDE GUI, may list “Restart Method” 315 as one of the availableactions. Clicking on the “Restart Method” option in the context menu 321may result in the resumption of execution at the start of thecurrently-executing method in at least some embodiments. In otherembodiments, if a method other than the currently-executing method isselected in a call stack window and the “Restart Method” option 315 isactivated from the context menu 321, execution may be resumed at theselected method.

FIG. 3 c illustrates another alternative approach that may beimplemented for restarting method UIs in some embodiments. In thedepicted example, a debugger-specific action menu 351, that may includea variety of debugger action options such as “Pause” (to pausedebug-mode execution), “Resume” (to resume debug-mode execution).“Suspend Breakpoints” and the like, may be enhanced by adding a “RestartMethod” option 315. The currently-executing method may be restartedusing this option in some embodiments. As in the case of FIG. 3 b, insome embodiments, a selected method other than the currently-executingmethod may be restarted in other embodiments.

FIG. 4 is a flow diagram illustrates aspects of operations that may beperformed to support restarts of invocable operations during debuggingsessions, according to at least some embodiments. As shown in element401, one or more user interfaces may be implemented to enable a user ofa debugger to submit, e.g., via single UI interaction, a request torestart a specified invocable operation such as a method or a function.The currently-executing method (or other invocable operation) may berestarted in some embodiments via the UI interaction, while in otherembodiments any selected invocable operation of the call stack of acurrent thread may be restarted.

A debugger 140 may receive a request via one of the UIs to restart aspecified invocable operation (element 404). In response, the debuggermay designate, as the source code line whose corresponding executableinstructions are to be executed next in the debugging session, the firstline of source code of the invocable operation for which executable codeexists (element 407). In at least some embodiments, the debugger mayprovide an indication to the user (element 410) of the source code linewhose executable instructions are to be run next—e.g., by moving acursor, a “next line symbol” 261 or its equivalent to the designatedline, or by highlighting the designated line.

In at least some embodiments, no new windows or panels may beinstantiated or opened as a result of the request to restart theinvocable operation. The debug-mode execution of the program may beresumed at the designated source code line (element 413).

In at least some embodiments, there may be a plurality of requests sentfrom the debugger to the debuggee or the VM in which the debuggee runsto accomplish the restart of the revocation operation. FIG. 5 is a flowdiagram illustrating operations performed to send requests to a debuggeeto restart an invocable operation, without instantiating any additionalgraphical user interface components, according to at least someembodiments. As shown in element 501, a request may be received via adebugger UI to restart a specified invocable operation O1. In response,a first debugging request may be sent (e.g., using JDI and/or JDWP to adebuggee running at a virtual machine) to pop the execution stack of thecurrent thread until the caller invocable operation O2, from which O1was invoked, reaches the top of the stack (element 504). Any GUIcomponent instantiations associated with popping the stack may besuppressed (element 507); i.e., the user may not be made aware that thestack is being popped in response to the restart request. In at leastsome embodiments, if the call stack is currently being displayed in aGUI component at the time that the request is received, any changes tothat call stack display may also be suppressed until the operationscorresponding to element 513 are performed.

After the request to pop the stack has been sent, in the depictedembodiment, another debugging request may be send to the debuggee, thistime to step from O2 into O1 (element 510). Once again, any GUIcomponent instantiation associated with the “step into O1” request maybe suppressed (element 513). The debug-mode execution of the program maythen be resumed at the first line of O1 with corresponding executableinstructions (element 514). Thus, in the depicted embodiment, the use ofthe separate debugging requests may not be revealed to the user of thedebugger; to the user, a single-step request to restart a specifiedmethod may appear to have a single-step response.

FIG. 5 is a block diagram illustrating a computing device 3000configured to implement a debugger 140 with support for the invocableoperation restart capability described above, according to at least someembodiments. The computing device 3000 may correspond to any of varioustypes of devices, including, but not limited to, a personal computersystem, desktop computer, laptop or notebook computer, mainframecomputer system, handheld computer, workstation, network computer, aconsumer device, application server, storage device, a peripheral devicesuch as a switch, modem, router, etc, or in general any type ofcomputing device. In the illustrated embodiment, computing device 3000includes one or more cores or processors 3010 (e.g., 3010 a, 3010 b, or3010 n) coupled to a system memory 3020 via an input/output (I/O)interface 3030. Computing device 3000 further includes a networkinterface 3040 coupled to I/O interface 3030.

In various embodiments, computing device 3000 may be a uniprocessorsystem including one processor 3010, or a multiprocessor systemincluding several cores or processors 3010 (e.g., two, four, eight, oranother suitable number). Processors 3010 may be any suitable processorscapable of executing instructions. For example, in various embodiments,processors 3010 may be general-purpose or embedded processorsimplementing any of a variety of instruction set architectures (ISAs),such as the SPARC, x86, PowerPC, or MIPS ISAs, or any other suitableISA. In multiprocessor systems, each of processors 3010 may commonly,but not necessarily, implement the same ISA.

System memory 3020 may be configured to store program instructionsimplementing the debugger 140 in the depicted embodiment. In someembodiments system memory may also store source code 3025 of variousprograms to be debugged, executable code 3028 of the programs, and/or anexecution environment 3027 similar to VM 110 of FIG. 1. System memorymay also include program instructions and/or data for various otherapplications. Program instructions may be encoded in platform nativebinary, any interpreted language such as Java™ bytecode, or in any otherlanguage such as C/C++, Java™, etc or in any combination thereof. Invarious embodiments, system memory 3020 may be implemented using anysuitable memory technology, such as static random access memory (SRAM),synchronous dynamic RAM (SDRAM), nonvolatile/Flash-type memory, or anyother type of memory.

In one embodiment, I/O interface 3030 may be configured to coordinateI/O traffic between processor 3010, system memory 3020, and anyperipheral devices in the device, including network interface 3040 orother peripheral interfaces. In some embodiments, I/O interface 3030 mayperform any necessary protocol, timing or other data transformations toconvert data signals from one component (e.g., system memory 3020) intoa format suitable for use by another component (e.g., processor 3010).In some embodiments, I/O interface 3030 may include support for devicesattached through various types of peripheral buses, such as a variant ofthe Peripheral Component Interconnect (PCI) bus standard or theUniversal Serial Bus (USB) standard, for example. In some embodiments,the function of I/O interface 3030 may be split into two or moreseparate components, such as a north bridge and a south bridge, forexample. Also, in some embodiments some or all of the functionality ofI/O interface 3030, such as an interface to system memory 3020, may beincorporated directly into processor 3010.

Network interface 3040 may be configured to allow data to be exchangedbetween computing device 3000 and other devices 3060 attached to anetwork or networks 3050, for example. Such other devices 3060 may hostthe debuggee program and/or a VM executing the debuggee program in someembodiments. In various embodiments, network interface 3040 may supportcommunication via any suitable wired or wireless general data networks,such as types of Ethernet network, for example. Additionally, networkinterface 3040 may support communication viatelecommunications/telephony networks such as analog voice networks ordigital fiber communications networks, via storage area networks such asFibre Channel SANs, or via any other suitable type of network and/orprotocol.

In some embodiments, system memory 3020 may be one embodiment of acomputer-accessible medium configured to store program instructions anddata as described above for FIG. 1 through FIG. 5 for implementingembodiments of the corresponding methods and apparatus. However, inother embodiments, program instructions and/or data may be received,sent or stored upon different types of computer-accessible media.Generally speaking, a computer-accessible medium may includenon-transitory storage media or memory media such as magnetic or opticalmedia, e.g., disk or DVD/CD coupled to computing device 3000 via I/Ointerface 3030. A non-transitory computer-accessible storage medium mayalso include any volatile or non-volatile media such as RAM (e.g. SDRAM,DDR SDRAM, RDRAM, SRAM, etc.), ROM, etc, that may be included in someembodiments of computing device 3000 as system memory 3020 or anothertype of memory. Further, a computer-accessible medium may includetransmission media or signals such as electrical, electromagnetic, ordigital signals, conveyed via a communication medium such as a networkand/or a wireless link, such as may be implemented via network interface3040. Portions or all of multiple computing devices such as thatillustrated in FIG. 6 may be used to implement the describedfunctionality in various embodiments; for example, software componentsrunning on a variety of different devices and servers may collaborate toprovide the functionality. In some embodiments, portions of thedescribed functionality may be implemented using storage devices,network devices, or special-purpose computer systems, in addition to orinstead of being implemented using general-purpose computer systems. Theterm “computing device”, as used herein, refers to at least all thesetypes of devices, and is not limited to these types of devices.

Various embodiments may further include receiving, sending or storinginstructions and/or data implemented in accordance with the foregoingdescription upon a computer-accessible medium. Generally speaking, acomputer-accessible medium may include storage media or memory mediasuch as magnetic or optical media, e.g., disk or DVD/CD-ROM, volatile ornon-volatile media such as RAM (e.g. SDRAM, DDR, RDRAM, SRAM, etc.),ROM, etc, as well as transmission media or signals such as electrical,electromagnetic, or digital signals, conveyed via a communication mediumsuch as network and/or a wireless link.

The various methods as illustrated in the Figures and described hereinrepresent example embodiments of methods. The methods may be implementedin software, hardware, or a combination thereof. The order of method maybe changed, and various elements may be added, reordered, combined,omitted, modified, etc.

Various modifications and changes may be made as would be obvious to aperson skilled in the art having the benefit of this disclosure. It isintended that the invention embrace all such modifications and changesand, accordingly, the above description to be regarded in anillustrative rather than a restrictive sense.

What is claimed is:
 1. A computer implemented method, comprising:implementing one or more user interfaces (UIs) enabling a user to submita request, via a single UI interaction within a debugging session of aprogram, to restart execution of an invocable operation included insource code of the program; and in response to a particular request torestart execution of a particular invocable operation of the sourcecode, received via a single UI interaction according to a particularuser interface of the one or more interfaces, wherein at least oneinstruction of the particular invocable operation has been executedpreviously during the debugging session: designating, as a next sourcecode line to be executed for debugging purposes during the debuggingsession, the first line of source code of the particular invocableoperation that corresponds to an executable operation, wherein saiddesignating comprises sending one or more debugging requests to avirtual machine at which the program is being executed, wherein the oneor more debugging requests comprise a first debugging request and asecond debugging request, wherein the first debugging request comprisesa request to pop the execution stack of the program to a callinginvocable operation from which the particular invocable operation iscalled, and wherein the second debugging request comprises a request tostep into the particular invocable operation; indicating, to a submitterof the particular request, that execution of the program being debuggedis to be resumed at the first line; and resuming execution of theprogram being debugged, in a debug mode, at the designated first line,such that the next line executed in the debugging session in response tothe particular request is the designated first line of the particularinvocable operation.
 2. The method as recited in claim 1, wherein anexecution environment of the program does not provide a capability tomove an execution point of the program to an arbitrary location withinthe program.
 3. The method as recited in claim 1, further comprising, atthe time that the particular request is received, displaying a set ofone or more graphical user interface (GUI) components, and wherein noadditional GUI components are instantiated in response to the particularrequest.
 4. The method as recited in claim 1, wherein the program iswritten in a platform-independent object-oriented programming language,and wherein the particular invocable operation comprises a method.
 5. Asystem, comprising: one or more processors; and memory coupled to theone or more processors, wherein the memory stores program instructionsthat when executed on the one or more processors cause the one or moreprocessors to implement a program debugger configured to: implement oneor more user interfaces (UIs) enabling a user to submit a request, via asingle UI interaction within a debugging session of a program, torestart execution of an invocable operation included in source code ofthe program; and in response to a particular request to restartexecution of a particular invocable operation of the source code,received via a single UI interaction according to a particular userinterface of the one or more interfaces, wherein at least oneinstruction of the particular invocable operation has been executedpreviously during the debugging session: designate, as a source codeline whose corresponding executable code is to be executed next duringthe debugging session, the first line of source code of the particularinvocable operation that corresponds to an executable operation, whereinto designate the first line as the next source code line to be executed,the debugger is configured to send one or more debugging requests to avirtual machine at which the program is being executed, wherein the oneor more debugging requests comprise a first debugging request and asecond debugging request, wherein the first debugging request comprisesa request to pop the execution stack of the program to a callinginvocable operation from which the particular invocable operation iscalled, and wherein the second debugging request comprises a request tostep into the particular invocable operation; indicate, to a submitterof the particular request, that execution of the program being debuggedis to be resumed at the first line; and resume execution of the programbeing debugged, in a debug mode, at the designated first line, such thatthe next line executed in the debugging session in response to theparticular request is the designated first line of the particularinvocable operation.
 6. The system as recited in claim 5, wherein anexecution environment of the program does not provide a capability tomove an execution point of the program to an arbitrary location withinthe program, and wherein a debugger architecture to which the programdebugger conforms does not provide a single-step interface enabling arestart of an invocable operation.
 7. The system as recited in claim 5,wherein the particular invocable operation is the current invocableoperation being executed in the debugging session at the time that theparticular request is received.
 8. The system as recited in claim 5,wherein, at the time that the particular request is received, thedebugger displays a set of one or more graphical user interface (GUI)components, and wherein no additional GUI components are instantiated inresponse to the particular request.
 9. The system as recited in claim 5,wherein the program is written in a platform-independent object-orientedprogramming language, and wherein the particular invocable operationcomprises a method.
 10. The system as recited in claim 5, wherein theone or more user interfaces includes a particular GUI componentdisplaying a current call stack of invocable operations, wherein theparticular invocable operation is displayed as a currently selectedoperation, and wherein the single UI interaction comprises requesting arestart action from a drop-down menu associated with the GUI component.11. The system as recited in claim 5, wherein the one or more userinterfaces includes a particular context-dependent GUI componentincluding a list of available actions, wherein the single UI interactioncomprises selecting an action, in the list of available actions, torestart a currently executing method.
 12. The system as recited in claim5, wherein the debugger is incorporated as a component of an integrateddevelopment environment (IDE).
 13. A non-transitory computer-readablestorage medium storing program instructions executable by one or moreprocessors to implement a debugger configured to: implement one or moreuser interfaces (UIs) enabling a user to submit a request, via a singleUI interaction within a debugging session of a program, to restartexecution of an invocable operation included in source code of theprogram; and in response to a particular request to restart execution ofa particular invocable operation of the source code, received via asingle UI interaction according to a particular user interface of theone or more interfaces, wherein at least one instruction of theparticular invocable operation has been executed previously during thedebugging session: designate, as a source code line whose correspondingexecutable code is to be executed next for debugging purposes during thedebugging session, the first line of source code of the particularinvocable operation that corresponds to an executable operation, whereinto designate the first line as the next source code line to be executed,the debugger is configured to send one or more debugging requests to avirtual machine at which the program is being executed, wherein the oneor more debugging requests comprise a first debugging request and asecond debugging request, wherein the first debugging request comprisesa request to pop the execution stack of the program to a callinginvocable operation from which the particular invocable operation iscalled, and wherein the second debugging request comprises a request tostep into the particular invocable operation; indicate, to a submitterof the particular request, that execution of the program being debuggedis to be resumed at the first line; and resume execution of the programbeing debugged, in a debug mode, at the designated first line, such thatthe next line executed in the debugging session in response to theparticular request is the designated first line of the particularinvocable operation.
 14. The non-transitory computer-readable storagemedium as recited in claim 13, wherein the particular invocableoperation is the current operation being executed in the debuggingsession at the time that the particular request is received.
 15. Thenon-transitory computer-readable storage medium as recited in claim 13,wherein, at the time that the particular request is received, thedebugger displays a set of one or more graphical user interface (GUI)components, and wherein no additional GUI components are instantiated inresponse to the particular request.
 16. The non-transitorycomputer-readable storage medium as recited in claim 13, wherein adebugger architecture to which the debugger conforms does not provide asingle-step interface enabling a restart of an invocable operation.